CAN_MessagePending
时间: 2024-01-30 07:01:45 浏览: 15
CAN_MessagePending是指CAN总线上是否有待发送的消息。在CAN协议中,当总线空闲时,所有与总线相连的单元都可以开始发送新消息。如果有多个单元同时开始发送消息,根据消息的标识符(ID)来决定优先级。发送高优先级ID消息的单元会获得发送权。如果所有的邮箱都已满,会使溢出标志位设置为1,需要等待有空邮箱。发送完成后,邮箱会变为空邮箱。因此,CAN_MessagePending可以用来判断是否有待发送的消息。\[1\]\[2\]\[3\]
#### 引用[.reference_title]
- *1* *2* *3* [CAN总线协议入门基础原理](https://blog.csdn.net/weixin_51121577/article/details/127362265)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v91^insert_down1,239^v3^insert_chatgpt"}} ] [.reference_item]
[ .reference_list ]
相关问题
stm32can通信
STM32是一款常用的微控制器,它支持CAN总线通信。在使用CAN通信时,需要配置CAN控制器和CAN过滤器,然后才能进行数据的发送和接收。以下是一个简单的CAN通信示例代码:
```c
#include "stm32f4xx.h"
void CAN_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
// 使能CAN1和GPIOB时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
// 配置PB8和PB9为复用功能
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
// 将PB8和PB9连接到CAN1的RX和TX引脚
GPIO_PinAFConfig(GPIOB, GPIO_PinSource8, GPIO_AF_CAN1);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource9, GPIO_AF_CAN1);
// 配置CAN1
CAN_InitStructure.CAN_TTCM = DISABLE; CAN_InitStructure.CAN_ABOM = DISABLE;
CAN_InitStructure.CAN_AWUM = DISABLE;
CAN_InitStructure.CAN_NART = DISABLE;
CAN_InitStructure.CAN_RFLM = DISABLE;
CAN_InitStructure.CAN_TXFP = DISABLE;
CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;
CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1 = CAN_BS1_6tq;
CAN_InitStructure.CAN_BS2 = CAN_BS2_8tq;
CAN_InitStructure.CAN_Prescaler = 4;
CAN_Init(CAN1, &CAN_InitStructure);
// 配置CAN过滤器
CAN_FilterInitStructure.CAN_FilterNumber = 0;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask; CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;
CAN_FilterInitStructure.CAN_FilterIdHigh = 0x0000;
CAN_FilterInitStructure.CAN_FilterIdLow = 0x0000;
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0x0000;
CAN_FilterInitStructure.CAN_FilterMaskIdLow = 0x0000;
CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
CAN_FilterInit(&CAN_FilterInitStructure);
}
void CAN_SendData(uint8_t* data, uint8_t len)
{
CanTxMsg TxMessage;
// 填充CAN消息结构体
TxMessage.StdId = 0x123;
TxMessage.ExtId = 0x00;
TxMessage.RTR = CAN_RTR_DATA;
TxMessage.IDE = CAN_ID_STD;
TxMessage.DLC = len;
for (int i = 0; i < len; i++) {
TxMessage.Data[i] = data[i];
}
// 发送CAN消息
while (CAN_Transmit(CAN1, &TxMessage) == CAN_TxStatus_NoMailBox);
}
void CAN_ReceiveData(uint8_t* data, uint8_t* len)
{
CanRxMsg RxMessage;
// 接收CAN消息
if (CAN_MessagePending(CAN1, CAN_FIFO0) > 0) {
CAN_Receive(CAN1, CAN_FIFO0, &RxMessage);
// 将数据拷贝到缓冲区
*len = RxMessage.DLC;
for (int i = 0; i < *len; i++) {
data[i] = RxMessage.Data[i];
}
}
}
int main(void)
{
uint8_t tx_data[] = {0x01, 0x02, 0x03};
uint8_t rx_data[8];
uint8_t rx_len;
CAN_Config();
while (1) {
CAN_SendData(tx_data, sizeof(tx_data));
CAN_ReceiveData(rx_data, &rx_len);
}
}
```
在上述代码中,CAN_Config函数用于配置CAN控制器和CAN过滤器,CAN_SendData函数用于发送CAN数据帧,CAN_ReceiveData函数用于接收CAN数据帧。
STM32 CAN 驱动程序
以下是一个简单的 STM32 CAN 驱动程序的示例,可以用于启用 CAN 总线并发送和接收 CAN 消息。注意,这个程序假设你已经在 STM32 上启用了 CAN 总线,并且已经配置了 CAN 控制器的时序和位宽等参数。
```c
#include "stm32f4xx.h"
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
CanTxMsg TxMessage;
CanRxMsg RxMessage;
void CAN_Config(void)
{
/* CAN Periph clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);
/* CAN1 Reset */
CAN_DeInit(CAN1);
/* CAN1 Init */
CAN_InitStructure.CAN_TTCM = DISABLE;
CAN_InitStructure.CAN_ABOM = DISABLE;
CAN_InitStructure.CAN_AWUM = DISABLE;
CAN_InitStructure.CAN_NART = DISABLE;
CAN_InitStructure.CAN_RFLM = DISABLE;
CAN_InitStructure.CAN_TXFP = DISABLE;
CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;
CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1 = CAN_BS1_9tq;
CAN_InitStructure.CAN_BS2 = CAN_BS2_4tq;
CAN_InitStructure.CAN_Prescaler = 4;
CAN_Init(CAN1, &CAN_InitStructure);
/* CAN filter init */
CAN_FilterInitStructure.CAN_FilterNumber = 0;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;
CAN_FilterInitStructure.CAN_FilterIdHigh = 0x0000;
CAN_FilterInitStructure.CAN_FilterIdLow = 0x0000;
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0x0000;
CAN_FilterInitStructure.CAN_FilterMaskIdLow = 0x0000;
CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
CAN_FilterInit(&CAN_FilterInitStructure);
/* Enable FIFO 0 message pending Interrupt */
CAN_ITConfig(CAN1, CAN_IT_FMP0, ENABLE);
}
void CAN_SendMsg(void)
{
/* Transmit */
TxMessage.StdId = 0x321;
TxMessage.RTR = CAN_RTR_DATA;
TxMessage.IDE = CAN_ID_STD;
TxMessage.DLC = 2;
TxMessage.Data[0] = 0xCA;
TxMessage.Data[1] = 0xFE;
CAN_Transmit(CAN1, &TxMessage);
}
void CAN_ReceiveMsg(void)
{
/* Receive */
while(CAN_MessagePending(CAN1, CAN_FIFO0) == 0);
CAN_Receive(CAN1, CAN_FIFO0, &RxMessage);
}
void CAN1_RX0_IRQHandler(void)
{
if (CAN_GetITStatus(CAN1, CAN_IT_FMP0) != RESET)
{
CAN_ReceiveMsg();
CAN_ClearITPendingBit(CAN1, CAN_IT_FMP0);
}
}
int main(void)
{
/* CAN Configuration */
CAN_Config();
/* Send Message */
CAN_SendMsg();
while (1)
{
/* Wait for reception of message */
if (CAN_MessagePending(CAN1, CAN_FIFO0) != 0)
{
/* Receive message */
CAN_ReceiveMsg();
}
}
}
```
该程序通过 `CAN_Config` 函数初始化 CAN 控制器和 CAN 滤波器,并通过 `CAN_SendMsg` 函数发送一个 CAN 消息。在主循环中,程序将等待接收 CAN 消息,并在接收到消息后调用 `CAN_ReceiveMsg` 函数进行处理。在 `CAN1_RX0_IRQHandler` 中断处理程序中,程序将检查是否有 CAN 消息待处理,并在接收到消息后调用 `CAN_ReceiveMsg` 函数进行处理。